Envoy HTTP: filter chain execution on reset streams causing UAF crash

Summary

Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, a logic vulnerability in Envoy's HTTP connection manager (FilterManager) that allows for Zombie Stream Filter Execution. This issue creates a "Use-After-Free" (UAF) or state-corruption window where filter callbacks are invoked on an HTTP stream that has already been logically reset and cleaned up. The vulnerability resides in source/common/http/filter_manager.cc within the FilterManager::decodeData method. The ActiveStream object remains valid in memory during the deferred deletion window. If a DATA frame arrives on this stream immediately after the reset (e.g., in the same packet processing cycle), the HTTP/2 codec invokes ActiveStream::decodeData, which cascades to FilterManager::decodeData. FilterManager::decodeData fails to check the saw_downstream_reset_ flag. It iterates over the decoder_filters_ list and invokes decodeData() on filters that have already received onDestroy(). This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.

Timeline

1. Mar 10, 2026, 7:14 PM UTCCVE published
2. Mar 10, 2026, 7:29 PM UTCCISA SSVC assessment

   Exploitation: poc · Automatable: no · Technical impact: partial

3. Mar 10, 2026, 7:34 PM UTCRecord last updated

Affected versions

• envoyproxy envoy

  From 1.37.0 · fixed in 1.37.1; From 1.36.0 · fixed in 1.36.5; From 1.35.0 · fixed in 1.35.9; fixed in 1.34.13

• github.com/envoyproxy/envoyGo

  1.37.0

• github.com/envoyproxy/envoyGo

  From 1.36.0 · through 1.36.4

• github.com/envoyproxy/envoyGo

  From 1.35.0 · through 1.35.8

• github.com/envoyproxy/envoyGo

  through 1.34.12

References 1